Shadow health secretary Andy Burnham and Yvette Cooper have thrown their hats into the ring in the battle for the Labour leadership - and Burnham had a dig at a potential rival in process.
In a video message announcing his candidacy, Burnham appeared to take a swipe at shadow education secretary Tristram Hunt, who has spoken of the need for the party to appeal to the "John Lewis couple" who shop in smart department stores, as well as its more traditional supporters.
Hunt has indicated he is considering joining the fight for the leadership.
Burnham announces his candidacy
Burnham said: "The party that I love has lost its emotional connection with millions of people.
"The way to get it back can't possibly be to choose one group of voters over another - to speak only to people on zero hour contracts or only to shoppers at John Lewis."
Burnham and Cooper join Chuka Umunna and Liz Kendall in the race to replace Ed Miliband, with the new leader to be announced at a special conference on September 12.
Following last week's disastrous general election, which prompted Miliband's resignation, Burnham said Labour had "lost its emotional connection with millions of people" and promised to "rediscover the beating heart of Labour".
In an apparent signal that he will seek to return the party to the election-winning approach adopted under Tony Blair, Burnham said he wanted Labour to "speak for everyone and for the whole country" and address voters' aspirations in the way it did in 1997.
He added: "Our challenge is not to go left or right, to focus on one part of the country above another, but to rediscover the beating heart of Labour.
"And that is about the aspirations of everyone, speaking to them like we did in 1997."
Stressing the need for Labour to help businesses grow and enable voters to pursue the dream of a better life, and for the party to renew its appeal to voters in Scotland - where it suffered near wipe-out at the hands of the SNP - he said: "Labour wins when it speaks to everyone and for the whole country, for Middle England but also Scotland, Wales and Northern Ireland.
"And it needs a leader whose voice can carry into all the nations and regions of the UK, be heard in every home. Someone who people can relate to, who understands their lives.
"I am that person. I can unite this country. And that's why I am standing to be leader of the Labour Party."
In a Daily Mirror article, Cooper said she wanted Labour to "move beyond the old labels of left and right" and be "credible, compassionate, creative and connected to the day-to-day realities of life".
She wrote: "In the end, Labour didn't convince enough people that we had the answers. They liked a lot of what we had to say, about raising the minimum wage, expanding childcare, cutting tax for low-paid workers and banning bad zero-hours contracts.
"But for many people it wasn't enough to give them hope and confidence we could match all their ambitions for the future.
"And when there's too little hope, optimism or confidence, the politics of anger, fear and division takes over - that's what the Tories, the SNP and Ukip all exploited and campaigned on in this election.
"The fracturing of politics reflects the fracturing of our country and our communities. Divided between rich and poor, north and south, city and small town. And it leaves Britain a darker, narrower place.
"But that's why Labour needs to be bigger in our appeal, bolder in our ambitions and brighter about the future.
"Going back to the remedies of the past, of Gordon Brown or Tony Blair, won't keep up with the way the world has changed. We need a Labour Party that moves beyond the old labels of left and right, and focuses four-square on the future. Credible, compassionate, creative, and connected to the day-to-day realities of life."
Burnham and Cooper's announcement came hours after Labour's ruling National Executive Committee agreed a four-month campaign to find a new leader and deputy leader under the new one-member-one-vote system adopted by the party last year.
Acting leader Harriet Harman said: "The general election saw the Labour Party suffer a serious defeat, and over the coming weeks we need an open and honest debate on the right way forward.
"Our challenge now is to use this time to listen and learn, to elect a new leader and deputy leader who will rebuild the Labour Party in order to take the fight to this Tory Government and to stand up for Britain."